Week 5 Notes

Command Line Editors

Action	Command
Show the Prompt	`P`
Command Format	`[addr[,addr]]cmd[params]`
Commands for location	`2` `.` `$` `%` `+` `-` `,` `;` `/RE/`
Commands for editing	`f` `p` `a` `c` `d` `i` `j` `s` `m` `u`
Execute a Shell command	`!command`
edit a file	`e filename`
read file contents into buffer	`r filename`
read command output into buffer	`r !command`
write buffer to filename	`w filename`
quit	`q`

man ed doesn’t give much info . Use info ed
ed test.txt shows a number indicating number of bytes read into memory
1 displays the first line
$ displays the last line
,p and %p shows the contents of the entire buffer
2,3p range - 2nd to 3rd line
/hello/ matches and shows first occurance of the pattern
+ and - to scroll by line
;p from current position to end of buffer
. displays the current line
!date running the date command within ed
r !date read output of date command to buffer at current position
w writes the file (saves it)
d delete current line
a to append after current line. Press . and enter when done
s/appended/Appended/ Substitute - Search and replace from current line.
f shows the name of the file being edited
p shows the contents of the current line
j for joining lines . Usage 5,6j to join line 5 and 6
m to move a line to a particular position. Usage m1 to move current line to just below line 1. m0 to move it right to the top
u to undo previous change
To add something to every line %s/$.*$/PREFIX \1/
- \1 is the back substitution
- $.*$ indicates any character that can be matched
- PREFIX is the replacement string
3,5s/PREFIX/prefix/ substitutes prefix for PREFIX from line 3 to 5

Command	Action
f	show name of file being edited
p	print the current line
a	append at the current line
c	change the line
d	delete the current line
i	insert line at the current position
j	join lines
s	search for regex pattern
m	move current line to position
u	undo latest change